In general, roof ridge vents work in conjunction with soffit vents in order to allow air to flow beneath the roof to provide passive ventilation. As hot stale air is withdrawn from the ridge slot vent by convection and/or wind suction, it is replaced by fresh ambient air through the soffit vents. This equalization inhibits moisture from condensing on insulation and wood roofing materials which causes mildew and rot, prevents build-up of ice dams which could buckle shingles and gutters, and reduces air-conditioning costs when hot attic air is replaced by cooler ambient air.
It has been known to ventilate attics under gable roofs made of contoured metal panels by running a vent along the roof ridge that is in communication with a slot or ridge opening that connects to the attic or under-roof space. A highly successful one of such vents which is manufactured and sold under the name “PROFILEVENT” is described in U.S. Pat. No. 5,561,953, which is incorporated by reference herein as if fully set forth, in which the contour of the metal roofing panel is cut into a non-woven strip of vent material. The vent material in this product is required to be stiff enough to hold its shape and resist crushing when the ridge cap is installed by nailing through the ridge cap and the vent material so that the net free area of the vent material is not diminished. The material is fire retardant, and the configuration is such that it prevents the ingress of wind driven-rain within the limits of the applicable building standards, and also prevents the ingress of debris and insects. To the extent that moisture penetrates into the non-woven material, it is freely draining so that it does not trap moisture against the metal roof panels which can occur with some of the known open cell foam vent products, which causes corrosion of the roof panels themselves, requiring costly repair or replacement. Further, this known product is UV stable and does not break down due to sunlight or environmental factors, such as hot and cold temperature exposure, which is an issue with some other ridge vent products made of open cell foam.
However, a drawback of the known “PROFILEVENT” material is that the profile is matched to the contoured roof panel in a direction parallel to the ridge, i.e., generally perpendicular to a direction that the contours or ribs of the roof panels extend. This does not allow the product to be used with a hip ridge vent, due to the angle it makes relative to the contoured roof panels, which can vary depending on the roof pitch, direction of the hip ridge, etc. This can result in insufficient ridge length being available for venting. Additionally, even with gable ridge vents, there is a higher cost involved with having to create vent material with the correct profile to match the known panel contours, as well as having to carry an inventory of vent material specific for each of such panel types.
Other known ridge vents use a porous foam strip or a non-woven mesh strip having enhanced flexibility that are compressed by the ridge cap to match a roof profile, for example of standing seam metal roofs. These arrangements can suffer issues with water retention causing roof decay in the case of foam, and incomplete filling of the profiled gap between the roof surface and the cap in which the ridge vent is installed for the non-woven mesh. Further, the enhanced flexibility of the non-woven mesh is due to the use of less fiber or smaller deniers of fiber and a reduced volume or more elastic binder to allow compressibility. This introduces additional issues with respect to the ability of the non-woven vent strip to prevent the entry of wind driven rain (WDR) as well as up slope-driven rain (USR) due to the more open non-woven material required for conformability as well as capillary action carrying moisture along the fibers, all of which can result in leakage through the vent.